Awesome
Kaniko image builder
This Action uses the kaniko executor instead of the docker daemon. Kaniko builds the image by extracting the filesystem of the base image, making the changes in the user space, snapshotting any change and appending it to the base image filesystem.
This allows for a quite efficient caching, that can be pushed to another docker registry and downloaded on-demand, and a noticeably easier and more secure secret passing to the build context, as it happens in the user space itself.
Usage
Example pipeline
name: Docker build
on: push
jobs:
docker:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@master
- name: Kaniko build
uses: aevea/action-kaniko@master
with:
image: aevea/kaniko
username: ${{ secrets.DOCKERHUB_USERNAME }}
password: ${{ secrets.DOCKERHUB_PASSWORD }}
cache: true
cache_registry: aevea/cache
Required Arguments
This action aims to be as flexible as possible, so it tries to define the defaults as for what I thought of being the most used values. So, technically there is a single required argument
variable | description | required | default |
---|---|---|---|
image | Name of the image you would like to push | true |
Optional Arguments
variable | description | required | default |
---|---|---|---|
registry | Docker registry where the image will be pushed | false | docker.io |
username | Username used for authentication to the Docker registry | false | $GITHUB_ACTOR |
password | Password used for authentication to the Docker registry | false | |
tag | Image tag | false | latest |
cache | Enables build cache | false | false |
cache_ttl | How long the cache should be considered valid | false | |
cache_registry | Docker registry meant to be used as cache | false | |
cache_directory | Filesystem path meant to be used as cache | false | |
build_file | Dockerfile filename | false | Dockerfile |
extra_args | Additional arguments to be passed to the kaniko executor | false | |
strip_tag_prefix | Prefix to be stripped from the tag | false | |
skip_unchanged_digest | Avoids pushing the image if the build generated the same digest | false | |
path | Path to the build context. Defaults to . | false | . |
tag_with_latest | Tags the built image with additional latest tag | false | |
target | Sets the target stage to build | false | |
debug | Enables trace for entrypoint.sh | false |
Here is where it gets specific, as the optional arguments become required depending on the registry targeted
docker.io
This is the default, and implicit docker registry, in the same way as with using the docker CLI In this case, the authentication credentials need to be passed via GitHub Action secrets
with:
image: aevea/kaniko
username: ${{ secrets.DOCKERHUB_USERNAME }}
password: ${{ secrets.DOCKERHUB_PASSWORD }}
NOTE: Dockerhub doesn't support more than one level deep of docker images, so Kaniko's default approach of pushing the cache to
$image/cache
doesn't work. If you want to use caching with Dockerhub, create acache
repository, and specify it in the action options.
with:
image: aevea/kaniko
username: ${{ secrets.DOCKERHUB_USERNAME }}
password: ${{ secrets.DOCKERHUB_PASSWORD }}
cache: true
cache_registry: aevea/cache
ghcr.io
GitHub's docker registry is a bit special. It doesn't allow top-level images, so this action will prefix any image with the GitHub namespace.
If you want to push your image like aevea/action-kaniko/kaniko
, you'll only need to pass kaniko
to this action.
The authentication is automatically done using the GITHUB_ACTOR
and GITHUB_TOKEN
provided from GitHub itself. But as GITHUB_TOKEN
is not
passed by default, it will have to be explicitly set up.
with:
registry: ghcr.io
password: ${{ secrets.GITHUB_TOKEN }}
image: kaniko
NOTE: GitHub's docker registry is structured a bit differently, but it has the same drawback as Dockerhub, and that's that it's not possible to "namespace" images for cache. In order to use registry cache, just specify the image meant to be used as cache, and Kaniko will push the cache layers to that image instead
with:
registry: ghcr.io
password: ${{ secrets.GITHUB_TOKEN }}
image: kaniko
cache: true
cache_registry: cache
registry.gitlab.com
GitLab's registry is quite flexible, it allows easy image namespacing, so a project's docker registry can hold up to three levels of image repository names.
registry.gitlab.com/group/project:some-tag
registry.gitlab.com/group/project/image:latest
registry.gitlab.com/group/project/my/image:rc1
To authenticate to it, a username and personal access token must be supplied via GitHub Action Secrets.
with:
registry: registry.gitlab.com
username: ${{ secrets.GL_REGISTRY_USERNAME }}
password: ${{ secrets.GL_REGISTRY_PASSWORD }}
image: aevea/kaniko
NOTE: As GitLab's registry does support namespacing, Kaniko can natively push cached layers to it, so only
cache: true
is necessary to be specified in order to use it.
with:
registry: registry.gitlab.com
username: ${{ secrets.GL_REGISTRY_USERNAME }}
password: ${{ secrets.GL_REGISTRY_PASSWORD }}
image: aevea/kaniko
cache: true
Other registries
If you would like to publish the image to other registries, these actions might be helpful
Registry | Action |
---|---|
Amazon Webservices Elastic Container Registry (ECR) | https://github.com/elgohr/ecr-login-action |
Google Cloud Container Registry | https://github.com/elgohr/gcloud-login-action |
Other arguments details
tag
The tag
argument, unless overridden, is automatically guessed based on the branch name. If the branch is master
then the tag will
be latest
, otherwise it will keep the branch name, but replacing any forward slash (/) with a hyphen (-).
If the v
prefix that it's usually added to the GitHub releases is not desired when pushed to dockerhub, the strip_tag_prefix
allows to
specify which part of the tag should be removed.
Example:
with:
registry: ghcr.io
password: ${{ secrets.GITHUB_TOKEN }}
image: kaniko
strip_tag_prefix: pre-
for the tag pre-0.1
will push kaniko:0.1
, as the pre-
part will be stripped from the tag name.
Outputs
image
Full reference to the built image with registry and tag.